The invention relates to a pressing device for a printing press or varnishing machine, which has a pressing roller for rolling a cylinder packing or dressing onto a circumferential surface of a cylinder, and has a finger protection device including a first flap and a second flap connected to the first flap via a swivel joint. The first flap, in a protective position, covers an inlet wedge or pocket jointly formed by the pressing roller and the cylinder.
German Published, Non-prosecuted Patent Application DE 100 18 923 A1 describes such a pressing device. However, in that device, it remains for the operator to bend the cylinder packing manually and without technical assistance into a cylinder gap formed in the cylinder and, in that regard, to force a trailing edge of the cylinder packing towards a clamping device disposed in the cylinder gap.
A pressing device described in German Published, Non-prosecuted Patent Application 2 156 044 has a similarly inconvenient type of operation.
It is accordingly an object of the invention to provide a pressing device for a printing press or varnishing machine, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which permits more comfortable tight clamping of the trailing edge of the cylinder packing.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a pressing device for a printing press or varnishing machine. The pressing device comprises a pressing roller for rolling a cylinder packing or dressing onto a circumferential surface of a cylinder, and a finger protection device including a first flap and a second flap connected to the first flap via a swivel joint. The first flap is formed as a pressing element for pressing the cylinder packing on the cylinder, and the first flap, in a protective position thereof, covers an inlet wedge or pocket jointly formed by the pressing roller and the cylinder.
In accordance with another feature of the invention, the first flap is mounted so as to be displaceable into a pressing position thereof wherein the first flap bears on the cylinder packing.
In accordance with a further feature of the invention, the first flap, in the pressing position thereof, is received in a cylinder gap formed in the cylinder.
In accordance with an added feature of the invention, the first flap, in the pressing position thereof, holds the cylinder packing on a clamping pad of a clamping device of the cylinder.
In accordance with an additional feature of the invention, the first flap, in the pressing position thereof, holds the cylinder packing bent into a cylinder gap formed in the cylinder.
In accordance with yet another feature of the invention, in a protective position of the first flap, a rolling element or a sliding element is disposed on the first flap. A spring holds the element in contact with a guide track.
In accordance with yet a further feature of the invention, the first flap is mounted so as to be swivelable about the swivel joint from the protective position into a switching position wherein the element is lifted off the guide track by overcoming the force of the spring.
In accordance with yet an added feature of the invention, in the protective position, the element is seated in a latching recess formed in the guide track.
In accordance with yet an additional feature of the invention, the guide track is a curved cam track of a cam, and the element is a cam follower element.
With the objects of the invention in view, there is also provided a printing press or a varnishing machine, comprising a pressing device. The pressing device includes a pressing roller for rolling a cylinder packing or dressing onto a circumferential surface of a cylinder, and a finger protection device including a first flap and a second flap connected to the first flap via a swivel joint. The first flap is formed as a pressing element for pressing the cylinder packing on the cylinder. The first flap, in a protective position thereof, covers an inlet wedge or pocket jointly formed by the pressing roller and the cylinder.
In the pressing device according to the invention, the first flap is multifunctional. The first flap serves, for one, for protecting the operator against injury and, for another, for making the work of the operator easier when a trailing edge of the cylinder packing is being clamped. A particularly compact construction of the pressing device is provided due to the multifunctionality. Only relatively little installation space is required within the printing press or varnishing machine for the integration of the pressing device. This compactness would not be provided in the case of a pressing device constructed differently from the pressing device according to the invention, which includes a pressing roller, a finger protection device and, in addition, a pressing element. In the case of the pressing device according to the invention, it is also advantageous that the pressing roller is available for rolling the cylinder packing on the cylinder, and the pressing element formed by the first flap is available for bending the cylinder packing into a cylinder gap of the cylinder and for pressing a trailing edge of the cylinder packing towards a clamping device disposed in the cylinder gap. Each of the two parts used to press the cylinder packing on the cylinder, i.e., the pressing roller and the pressing element, is optimally constructed with respect to the specific task thereof. The pressing roller is specifically constructed for rolling the cylinder packing onto the circumferential surface of the cylinder. The pressing element formed by the finger protection device is specifically constructed for bending the cylinder packing near the trailing edge thereof. In a pressing device wherein a pressing roller and a pressing element, differing from those of the invention, were not two different parts but one and the same part, construction compromises would have to be made and, therefore, functional deficiencies with respect to each of the individual functions, the rolling and the bending, would have to be accepted.
The pressing roller of the pressing device according to the invention is a pressing roller that is different from a rubber or blanket cylinder, i.e., it is not a rubber or blanket cylinder.
The cylinder packing may be a printing plate, for example, an offset printing plate, or a flexographic printing plate used for varnishing or a rubber blanket used, for example, for varnishing. Accordingly, the cylinder is a plate or blanket cylinder.
Advantageous developments of the pressing device according to the invention are noted hereinbelow.
One development is distinguished by the fact that the first flap is mounted so as to be adjustable into a pressing position, wherein the first flap bears on the cylinder packing.
The content of a further development is that in the pressing position the first flap is received in or dips into a cylinder gap of the cylinder.
According to a further development, in the pressing position, the cylinder packing is held by the first flap on a clamping pad of a clamping device of the cylinder.
The fact that, in the pressing position, the cylinder packing is held bent by the first flap in the cylinder gap formed in the cylinder distinguishes a further development.
The content of a further development is that, in the protective position, a rolling or sliding element disposed on the first flap is held by a spring in contact with a guide track.
A further development is that the first flap is mounted so that it is swivelable about the joint from the protective position into a switching position, wherein the rolling or sliding element is raised off the guide track when overcoming the force of the spring.
According to one development, provision is made for the rolling or sliding element to be seated in a latching recess in the guide track when in the protective position. The guide track may be a curved cam track of a cam, and the rolling or sliding element may be a cam follower element.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a pressing device for a printing press or varnishing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.